A Pseudowire (PW) is an emulation of a native service over a Packet Switched Network (PSN). The native service may be a layer 2 or Synchronous Optical Networking (SONET) connection, Asynchronous Transfer Mode (ATM), Frame Relay, Ethernet, low-rate Time-Division Multiplexing (TDM), or SONET/Synchronous Digital Hierarchy (SDH), while the PSN may be Multiprotocol Label Switching (MPLS), Internet Protocol (IP) (either IPv4 or IPv6), or Layer 2 Tunnel Protocol Version 3 (L2TPv3). More particularly, a pseudowire is a tunnel established between two provider-edge (PE) nodes to transport Layer 2 Protocol Data Units (PDUs) across a packet switched network (PSN).
A multi-segmented pseudowire (MS-PW) is one which traverses multiple PSN domains, i.e., one or more Service Provider (SP) networks, or multiple networks within the same SP network (e.g. an access and core network). More specifically a MS-PW is a static or dynamically configured set of two or more contiguous pseudowire segments that behave and function as a single point-to-point pseudowire. Each end of a MS-PW terminates at an Ultimate Provider Edge (U-PE) device.
Pseudowires may be established using a variety of processes including by static configuration (using MPLS or L2TPv3) or by Label Distribution Protocol (LDP). LDP defines two Forwarding Equivalency Class (FEC) elements which may be used to establish pseudowires; PWid FEC 128 and Generalized PWid FEC 129. As the standards for pseudowire signaling continues to evolve, deployed network devices may execute different LDP pseudowire signaling protocols. It is desirable to identify a method that enables MS-PW to extend between PSN domains that use different pseudowire signaling protocols.